It is often desirable to imprint a magnetic pattern onto a medium (e.g., a disk, a tape, a credit card) in a predictable and reproducible manner. One approach to imprinting a magnetic pattern onto a medium is servo media printing. In servo media printing, the medium is first exposed to a magnetic field to form a uniform direction of pre-magnetization in the medium. The pre-magnetized medium is then contacted with a master for servo printing, and the pre-magnetized medium is exposed to a uniform magnetic field through the master. Typically, the uniform magnetic field is in a direction opposite to the direction of pre-magnetization of the medium.
The master for servo printing usually includes a substrate and a pattern of teeth disposed on the substrate. In general, the substrate is formed of a non-ferromagnetic material, and the teeth are formed of a ferromagnetic material. During servo printing, the pattern of ferromagnetic teeth in the master interacts with the uniform magnetic field to form a magnetic pattern in the recording medium.
In one type of servo printing, typically referred to as longitudinal media printing, the direction of pre-magnetization in the recording medium is parallel to the surface of the recording medium that contacts the master during the printing process. Ideally, after longitudinal media printing, the portions of the recording medium that were beneath the teeth during the printing process remain magnetized in the direction of pre-magnetization, and the portions of the medium that were not beneath the pattern of teeth during the printing process are magnetized in the direction of the uniform magnetic field.
In another type of printed media servo printing, often referred to as perpendicular media printing, the direction of pre-magnetization in the medium is perpendicular to the surface of the recording medium that contacts the master during the printing process. Ideally, after perpendicular media printing, the portions of the recording medium that were not beneath the pattern of teeth during the printing process remain magnetized in the direction of pre-magnetization, and the portions of the medium that were beneath the pattern of teeth during the printing process are magnetized in the direction of the uniform magnetic field.